This invention relates to recording and playback of multi-channel digital audio having different resolutions for different channels and concerns digital recording media generally like digital versatile discs. More particularly, this invention concerns such recording media that primarily contain audio information.
Commonly assigned McPherson et al. U.S. patent application Ser. No. 09/066,041, filed Apr. 24, 1998 and Thagard et al. U.S. patent application Ser. No. 09/066,043, filed Apr. 24, 1998 are incorporated herein by reference.
Digital versatile discs (xe2x80x9cDVDsxe2x80x9d) are two-sided high-density digital information recording media approximately the size of standard compact discs (xe2x80x9cCDsxe2x80x9d). Digital versatile discs are capable of holding approximately 4.7 gigabytes of data per side. Their large storage capacity and small size make DVDs attractive for replacing videocassette tapes for use in home video systems.
DVDs support the Moving Picture Experts Group (xe2x80x9cMPEGxe2x80x9d) MPEG-2 digital video standard. DVDs are also capable of handling Dolby""s AC-3 multichannel audio format or, alternatively, an uncompressed pulse code modulation (xe2x80x9cPCMxe2x80x9d) encoded dual-channel format.
However, because standard DVDs are directed primarily toward supporting the storage and display of video content, standard DVDs are not particularly well suited for supporting content that is primarily audio, especially enhanced audio, such as six-channel audio, including sampling at rates that are higher than those that have been conventionally used.
It is therefore an object of the present invention to provide methods and apparatus for recording that use DVD-type technology but that are better adapted for handling content that is primarily audio.
This and other objects of the present invention are accomplished in accordance with the principles of the invention by providing methods and apparatus for recording on DVD-like recording media in which audio content is stored in a high-capacity multi-channel (e.g., six-channel) format. An example of such a high-capacity multi-channel system is a six-channel system in which the six channels may be represented by uncompressed data (e.g., PCM data). Each channel may be encoded at a different rate. For example, the front and center channels may use 96 KHz encoding, the rear channels may use 48 KHz encoding, and the subwoofer channel may use 12 KHz encoding. Each channel may use a separate data depth. For example, the front and center channels may be encoded using 20-bit words and the rear channels may be encoded using 16-bit words.
If desired, a two-channel audio output may be derived from the six-channel audio data stream during playback. To facilitate an accurate derivation, the mixing coefficients to be used in generating the derivation can be supplied along with the six-channel audio data.
Alternatively, six-channel audio tracks may be accompanied by two-channel audio tracks having essentially the same content as the six-channel tracks. The recording media of the present invention allows this additional two-channel audio track to be stored in multiple formats, so that producers of audio content and disc manufacturers have multiple two-channel encoding options.
Further features of the invention, its nature and various advantages will be more apparent from the following more detailed description.